The present invention relates generally to air handling systems, and more particularly to air conditioners that are variably adjustable over a range of operating speeds to blow air at desired rates.
Conventional air conditioners include a refrigeration unit, a motor driven fan to direct air over a heat exchanger cooled by the refrigeration unit, intake and exhaust ports, and a control portion to allow an operator to select a predetermined operational speed of the fan. The air conditioner is controlled according to a relationship between a desired temperature setting input via the control portion, and a temperature of the room to be cooled as sensed by a thermistor. When the sensed temperature exceeds the desired temperature by a predetermined value, the refrigeration unit is activated to cool the heat exchanger which, in turn, cools air being directed over the heat exchanger by the fan. The refrigeration unit is deactivated when the sensed temperature falls below a predetermined value related to the set temperature.
While the refrigeration unit is usually operated between on and off states, the control portion allows the fan to be operated at a number preprogrammed fan speed settings that are selectable depending on the degree of cooling desired. In hot environments such as a room having windows through which sunlight directly enters the room, a first, high setting can be selected to operate the fan motor near its maximum speed. When a minimal amount of cooling is desired, the control portion can be adjusted to operate the fan motor at a second, low speed. Similarly, in moderate temperature environments, the control portion can be adjusted to another discrete, mid level setting to operate the fan motor at an intermediate speed between the maximum and minimum speeds. Adjustment between the fan motor speed is sudden and requires the user to select one of the preprogrammed speeds, which are often too fast or too slow to satisfy particular cooling demands.
When the refrigeration unit is operated for a prolonged period of time, humidity in air passing through the air conditioner can condense and freeze on a heat exchanging surface of the heat exchanger. As the frozen humidity accumulates, the ability of the heat exchanger to transfer heat to air being blown over the heat exchanger is impaired, thus affecting the cooling ability of the air conditioner.
Prolonged operation of the air conditioner at a single set temperature may not be desirable. As occupants of a room sleep, their bodily functions slow down, causing a drop in body temperature. The air conditioner operating at the set temperature continues to discharge cool air into the room when the cool air is not needed. The operation of the air conditioner at the set temperature during a period of time when cool air is not needed leads to wasted electrical energy and discomfort to those sleeping in the room.
The size of air conditioner selected for a particular application depends on the size of the area to be cooled. Components, including the motor for driving the fan, will be sized to meet the cooling demands of the area in which the air conditioner is to be installed. As the cooling demands increase, so must the size of the fan motor installed in a particular air conditioner to move a sufficient amount of air over the heat exchanger to satisfy the cooling demands. This requires a manufacturer of air conditioners to warehouse components such as fan motors of different sizes and ratings to allow the installation of suitably sized fan motors across an entire line of products.
When the air conditioner is operating, visual identification of the selected operating speed of the fan motor is not visible from a distance away from the air conditioner. Switches or rotatable knobs provided to a front of the air conditioner are small, and typically disposed within a housing accessible through a pivoting door. To view or adjust the selected operating speed of the fan in a dimly lit room one must approach the air conditioner with a light.
Accordingly, it would be beneficial to provide an air conditioner having a fan motor that can be substantially continuously adjusted to a speed within a range of speeds to accurately meet the cooling demands where the air conditioner is installed. The air conditioner should be adjustable via a user interface at the front of the air conditioner and from a remote location, provided with frost protection to minimize the accumulation of frost on a heat exchanging surface, and should be capable of accepting components that will efficiently meet the cooling demands of a plurality of environments. Further, the fan speed should be visible from a distance from the air conditioner.